WASHINGTON (Reuters) - U.S. Commerce Secretary Wilbur Ross on Thursday said a U.S. national security probe of car and truck imports was still in its early stages but that other countries’ high, artificial barriers such as tariffs and other interventions have skewed the marketplace.

“Now it’s very difficult to get back to a reciprocal arrangement,” Ross said in an interview on CNBC, a day after announcing the investigation, which could lead to new U.S. tariffs on imported automobiles.

The probe, launched under Section 232 of the Trade Expansion Act of 1962, will look at whether vehicle and parts imports are threatening the industry’s health and ability to research and develop advanced technologies, Ross said on Wednesday.

Shares of automakers in Asia and Europe were lower on Thursday following the announcement of the investigation, which could lead to tariffs like those imposed on steel and aluminum earlier this year.

Shares of General Motors Co (GM.N) and Ford Motor Co (F.N) were only marginally higher before the bell on Thursday.

Ross said he did not blame other countries for the imbalance in autos, saying they were doing what was best for themselves. In addition to tariffs, Ross cited other non-tariff barriers such as standards, licensing and “all kinds of other games.”

“The stupidity is that we let ourselves get into this box of extremely low rates,” he told CNBC.